Christopher S. Hall
8006c24595
time: Add driver cross timestamp interface for higher precision time synchronization ...
ACKNOWLEDGMENT: cross timestamp code was developed by Thomas Gleixner
<tglx@linutronix.de>. It has changed considerably and any mistakes are
mine.
The precision with which events on multiple networked systems can be
synchronized using, as an example, PTP (IEEE 1588, 802.1AS) is limited
by the precision of the cross timestamps between the system clock and
the device (timestamp) clock. Precision here is the degree of
simultaneity when capturing the cross timestamp.
Currently the PTP cross timestamp is captured in software using the
PTP device driver ioctl PTP_SYS_OFFSET. Reads of the device clock are
interleaved with reads of the realtime clock. At best, the precision
of this cross timestamp is on the order of several microseconds due to
software latencies. Sub-microsecond precision is required for
industrial control and some media applications. To achieve this level
of precision hardware supported cross timestamping is needed.
The function get_device_system_crosstimestamp() allows device drivers
to return a cross timestamp with system time properly scaled to
nanoseconds. The realtime value is needed to discipline that clock
using PTP and the monotonic raw value is used for applications that
don't require a "real" time, but need an unadjusted clock time. The
get_device_system_crosstimestamp() code calls back into the driver to
ensure that the system counter is within the current timekeeping
update interval.
Modern Intel hardware provides an Always Running Timer (ART) which is
exactly related to TSC through a known frequency ratio. The ART is
routed to devices on the system and is used to precisely and
simultaneously capture the device clock with the ART.
Cc: Prarit Bhargava <prarit@redhat.com>
Cc: Richard Cochran <richardcochran@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Andy Lutomirski <luto@amacapital.net>
Cc: kevin.b.stanton@intel.com
Cc: kevin.j.clarke@intel.com
Cc: hpa@zytor.com
Cc: jeffrey.t.kirsher@intel.com
Cc: netdev@vger.kernel.org
Reviewed-by: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Christopher S. Hall <christopher.s.hall@intel.com>
[jstultz: Reworked to remove extra structures and simplify calling]
Signed-off-by: John Stultz <john.stultz@linaro.org>
2016-03-02 17:13:10 -08:00
net: bpf: reject invalid shifts
2016-01-12 17:06:53 -05:00
module: use a structure to encapsulate layout.
2015-12-04 22:46:25 +01:00
wrappers for ->i_mutex access
2016-01-22 18:04:28 -05:00
gcov: use within_module() helper.
2015-12-04 22:46:25 +01:00
PCI changes for the v4.5 merge window:
2016-01-21 11:52:16 -08:00
livepatch: Cleanup module page permission changes
2015-12-04 22:51:07 +01:00
Merge branch 'locking-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip
2016-01-11 14:18:38 -08:00
PM / sleep: Add support for read-only sysfs attributes
2016-01-04 22:28:59 +01:00
kernel: printk: specify alignment for struct printk_log
2016-01-20 17:09:18 -08:00
Merge branches 'doc.2015.12.05a', 'exp.2015.12.07a', 'fixes.2015.12.07a', 'list.2015.12.04b' and 'torture.2015.12.05a' into HEAD
2015-12-07 17:02:54 -08:00
wrappers for ->i_mutex access
2016-01-22 18:04:28 -05:00
time: Add driver cross timestamp interface for higher precision time synchronization
2016-03-02 17:13:10 -08:00
Not much new with tracing for this release. Mostly just clean ups and
2016-01-12 20:04:15 -08:00
certs: add .gitignore to stop git nagging about x509_certificate_list
2015-10-21 15:18:35 +01:00
async: export current_is_async()
2015-11-19 17:51:48 +01:00
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security
2016-01-17 19:13:15 -08:00
security: Make inode argument of inode_getsecid non-const
2015-12-24 11:09:39 -05:00
wrappers for ->i_mutex access
2016-01-22 18:04:28 -05:00
audit: audit_tree_match can be boolean
2015-11-04 08:23:51 -05:00
wrappers for ->i_mutex access
2016-01-22 18:04:28 -05:00
audit: fix comment block whitespace
2015-11-04 08:23:51 -05:00
security: Make inode argument of inode_getsecid non-const
2015-12-24 11:09:39 -05:00
Merge branch 'for-4.5' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
2016-01-12 19:20:32 -08:00
cgroup: kill cgrp_ss_priv[CGROUP_CANFORK_COUNT] and friends
2015-12-03 10:24:08 -05:00
cgroup_pids: fix a typo.
2015-12-14 14:54:37 -05:00
context_tracking: Switch to new static_branch API
2015-11-24 09:56:43 +01:00
kernel/cpu.c: make set_cpu_* static inlines
2016-01-20 17:09:18 -08:00
Merge branch 'for-4.4-fixes' into for-4.5
2015-12-03 10:22:52 -05:00
kmemcg: account certain kmem allocations to memcg
2016-01-14 16:00:49 -08:00
kmemcg: account certain kmem allocations to memcg
2016-01-14 16:00:49 -08:00
exit: remove unneeded declaration of exit_mm()
2016-01-20 17:09:18 -08:00
mm: rework virtual memory accounting
2016-01-14 16:00:49 -08:00
ptrace: use fsuid, fsgid, effective creds for fs access checks
2016-01-20 17:09:18 -08:00
ptrace: use fsuid, fsgid, effective creds for fs access checks
2016-01-20 17:09:18 -08:00
treewide: Remove old email address
2015-11-23 09:44:58 +01:00
treewide: Remove old email address
2015-11-23 09:44:58 +01:00
ptrace: use fsuid, fsgid, effective creds for fs access checks
2016-01-20 17:09:18 -08:00
kexec: set KEXEC_TYPE_CRASH before sanity_check_segment_list()
2016-01-20 17:09:18 -08:00
kernel/kexec_core.c: use list_for_each_entry_safe in kimage_free_page_list
2016-01-20 17:09:18 -08:00
kexec: move some memembers and definitions within the scope of CONFIG_KEXEC_FILE
2016-01-20 17:09:18 -08:00
kexec: move some memembers and definitions within the scope of CONFIG_KEXEC_FILE
2016-01-20 17:09:18 -08:00
kmod: don't run async usermode helper as a child of kworker thread
2015-10-23 17:55:10 +09:00
rcu: Remove TINY_RCU bloat from pointless boot parameters
2015-12-07 16:59:37 -08:00
mm, x86: get_user_pages() for dax mappings
2016-01-15 17:56:32 -08:00
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/jikos/livepatching
2016-01-14 16:38:02 -08:00
KEYS: Merge the type-specific data with the payload data
2015-10-21 15:18:36 +01:00
printk: do cond_resched() between lines while outputting to consoles
2016-01-16 11:17:25 -08:00
Nothing exciting, minor tweaks and cleanups.
2015-11-09 15:53:39 -08:00
kmemcg: account certain kmem allocations to memcg
2016-01-14 16:00:49 -08:00
ptrace: use fsuid, fsgid, effective creds for fs access checks
2016-01-20 17:09:18 -08:00
wrappers for ->i_mutex access
2016-01-22 18:04:28 -05:00
restrict /dev/mem to idle io memory ranges
2016-01-09 06:30:49 -08:00
seccomp, ptrace: add support for dumping seccomp filters
2015-10-27 19:55:13 -07:00
kernel/signal.c: unexport sigsuspend()
2015-11-20 16:17:32 -08:00
mm, page_alloc: distinguish between being unable to sleep, unwilling to sleep and avoiding waking kswapd
2015-11-06 17:50:42 -08:00
stop_machine: Kill smp_hotplug_thread->pre_unpark, introduce stop_machine_unpark()
2015-10-20 10:23:55 +02:00
kernel/stop_machine.c: remove CONFIG_SMP dependencies
2016-01-16 11:17:24 -08:00
prctl: take mmap sem for writing to protect against others
2016-01-20 17:09:18 -08:00
vfs: add copy_file_range syscall and vfs helper
2015-12-01 14:00:53 -05:00
Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs
2016-01-22 10:24:03 -08:00
torture: Consolidate cond_resched_rcu_qs() into stutter_wait()
2015-10-06 11:25:01 -07:00
tracepoint: Give priority to probes of tracepoints
2015-10-25 21:33:54 -04:00
kernel/*: switch to memdup_user_nul()
2016-01-04 10:27:55 -05:00
Merge branch 'for-4.5' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/wq
2016-01-11 18:53:13 -08:00
workqueue: simplify the apply_workqueue_attrs_locked()
2016-01-07 11:04:34 -05:00
8006c24595